8
Operation
Sequence of Operation
1. The VLF ventless hood receives power from the eld
wiring block of a single, or top of a double stack, vent-
less ready oven. This received power runs to the
front panel circuit breaker of the VLF and must be in
the ON position in order for the hood to operate.
2. The VLF has an interlock switch that engages when
the hood’s lter is properly installed. The lter inter-
lock switch must also be engaged in order for the
hood to operate.
3. Provided 1 and 2 above are satised, turning on ei-
ther the top or bottom ventless ready oven of a double
stack or the single ventless ready oven will start the
oven’s convection blower motor, closing the motor’s
proof of rotation switch which will turn on the hood’s
blower motor.
4. When the VLF blower turns on it creates a pressure
dierential between the plenum above and the ple-
num below the hood’s lter. The upper and lower
plenum pressure taps are connected to two pressure
switches, one has a pressure setpoint of 0.40”W.C.
and the other has a pressure setpoint of 0.25”W.C.
The 0.40”W.C. pressure switch is interlocked with the
oven’s call for heat. For a new lter, the dierential
pressure is low because airow is nearly uninhibited.
This very low pressure will cause no change in either
switch, which will allow the oven to heat and operate
normally.
5. As the VLF’s lter becomes obstructed through use,
the dierential pressure across the lter will rise.
When this dierential pressure reaches 0.25”W.C.,
the orange indicator light, labeled “Order New Filter”,
will illuminate on the front panel of the hood
6. As the VLF’s lter becomes further obstructed from
usage, the dierential pressure will continue to rise.
When this dierential pressure reaches 0.40”W.C.,
the red indicator light, labeled “Change Filter To Use
Oven”, will illuminate on the front panel of the hood.
Once the red indicator is illuminated the oven’s/ov-
ens’ call for heat will disengage. The oven(s) will still
operate but will not heat.
